Index

#ignition   #ros2   #bridge  

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Table of Content

ROS2 ignition/gz bridge

ros_ign contains packages that provide integration between ROS2 and Ignition:

• ros_ign: Metapackage that provides all other software packages;
• ros_ign_image: Use image_transport to transfer the image from Ignition to the one-way transmission bridge of ROS;
• ros_ign_bridge: Two-way transmission bridge between Ignition and ROS;
• ros_ign_gazebo: It is convenient to use the startup files and executable files of Ignition Gazebo and ROS;
• ros_ign_gazebo_demos: Demos using ROS-Ignition integration;
• ros_ign_point_cloud: A plug-in used to simulate publishing point clouds to ROS from Ignition Gazebo

install

sudo apt install ros-humble-ros-gz

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Demo

Pub keypress from gazebo fortress to ROS2 using bridge - Load bridge with mapping - Open Terminal with ROS echo command - For testing open anther Terminal with ign echo command - Run gazebo with key press plugin - Press anywhere on gazebo , both subscriber window show the keypress code

run bridge

# <topic name>@<ros2 type>@<gz type>
ros2 run ros_gz_bridge parameter_bridge \
/keyboard/keypress@std_msgs/msg/Int32@ignition.msgs.Int32

ros subscriber

ros2 topic echo /keyboard/keypress

ign echo (subscriber)

ign topic -e --topic /keyboard/keypress

ign gazebo empty.sdf

using yaml config

ign2ros_bridge.yaml

- topic_name: /keyboard/keypress
  ros_type_name: std_msgs/msg/Int32
  ign_type_name: ignition.msgs.Int32
  direction: BIDIRECTIONAL

```bash name=”Terminal1: Run bridge ros2 run ros_gz_bridge
bridge_node
–ros-args
-p config_file:=$PWD/src/gz_demos/config/ign2ros_bridge.yaml

```bash title="Terminal2 ROS echo"
ros2 topic echo /keyboard/keypress

Terminal3 ign pub

ign topic  -t /keyboard/keypress --msgtype ignition.msgs.Int32 -p "data: 102"

---

Demo: using ROS2 launch file

simple_bridge.launch.py

import os
from ament_index_python.packages import get_package_share_directory
from launch import LaunchDescription
from launch_ros.actions import Node


def generate_launch_description():
    ld = LaunchDescription()

    # Bridge
    bridge = Node(
        package="ros_gz_bridge",
        executable="parameter_bridge",
        arguments=[
            "/keyboard/keypress@std_msgs/msg/Int32@ignition.msgs.Int32",
        ],
        output="screen",
    )

    ld.add_action(bridge)
    return ld

Pub from Gazebo to ROS2

Terminal1

ros2 launch gz_demos simple_bridge.launch.py

Terminal2

ros2 topic echo /keyboard/keypress

Terminal3

ign topic  -t /keyboard/keypress --msgtype ignition.msgs.Int32 -p "data: 1021"

Pub from ROS2 to Gazebo

Terminal2

ign topic -e --topic /keyboard/keypress

Terminal3

ros2 topic pub /keyboard/keypress std_msgs/msg/Int32 "{data: 100}"

---

Demo: ROS2 launch and bridge YAML config

Example and idea from gazebosim

bridge with yaml

import os
from ament_index_python.packages import get_package_share_directory
from launch import LaunchDescription
from launch.actions import ExecuteProcess


def generate_launch_description():
    ld = LaunchDescription()

    config = os.path.join(
        get_package_share_directory('gz_demos'),
        'config',
        'ign2ros_bridge.yaml'
        )

    # Bridge
    bridge = ExecuteProcess(
        cmd=[
            'ros2 run ros_gz_bridge parameter_bridge  --ros-args -p config_file:={}'.format(config)
            ],
        output='screen',
        shell=True
    )

    ld.add_action(bridge)
    return ld

Reference

• /ros_gz_bridge